美国宇航局在银河系中心发现“宇宙拐杖糖”

美国宇航局在银河系中心发现“宇宙拐杖糖”

Here's a holiday card from 27,000 light-years away, offering a little yuletide cheer and astronomical intrigue from the mysterious central zone of the Milky Way. The composite image above shows an enormous swath of the galactic center, spanning about 750 light-years across, where a giant "cosmic candy cane" stands out among colorful molecular clouds.

这是一张27000光年外的节日贺卡，上面有来自银河系神秘中心地带的一点圣诞节的欢乐和天文学的神秘。上面的合成图像显示了银河系中心的一条巨大的狭长地带，横跨约750光年，其中一个巨大的“宇宙拐杖糖”在彩色分子云中脱颖而出。

Photo: NASA’s Goddard Space Flight Center

This festive scene was captured by a NASA camera, the Goddard-IRAM Superconducting 2-Millimeter Observer (GISMO). It's the subject of two scientific studies — one led by Johannes Staguhn of Johns Hopkins University, and one led by Richard Arendt at the University of Maryland — both recently published in The Astrophysical Journal.

这一喜庆的场景是由美国宇航局的一台名为Goddard-IRAM超导2毫米观测者(GISMO)的照相机拍摄的。这是两项科学研究的主题——一项由约翰霍普金斯大学的约翰内斯·斯塔古恩领导，另一项由马里兰大学的理查德·阿伦特领导——两项研究最近都发表在《天体物理学杂志》上。

The image offers a rare glimpse into the bustling downtown Milky Way, home to the largest and densest collection of molecular clouds in our galaxy. These cold, colossal structures can give birth to new stars, and the molecular clouds in this image hold enough dense gas and dust to form tens of millions of stars like our sun, according to NASA.

这张照片为我们提供了一个难得的机会，让我们得以一窥熙熙攘攘的银河系中心，这里是我们星系中分子云最庞大、密度最大的地方。据美国国家航空航天局称，这些冰冷、巨大的结构可以孕育出新的恒星，而这幅图像中的分子云含有足够的稠密气体和尘埃，足以形成数千万颗像我们的太阳一样的恒星。

"The galactic center is an enigmatic region with extreme conditions where velocities are higher and objects frequently collide with one another," says Staguhn, a research scientist at Johns Hopkins who also leads the GISMO team at NASA's Goddard Space Flight Center, in a statement. "GISMO gives us the opportunity to observe microwaves with a wavelength of 2 millimeters at a large scale, combined with an angular resolution that perfectly matches the size of galactic center features we are interested in. Such detailed, large-scale observations have never been done before."

“银河系中心是一个神秘的区域，在极端条件下，速度更高，物体之间经常发生碰撞，”约翰霍普金斯大学的研究科学家斯塔格恩在一份声明中说，他同时也是美国宇航局戈达德太空飞行中心GISMO团队的负责人。“GISMO让我们有机会在大尺度上观察到波长为2毫米的微波，再加上与我们感兴趣的星系中心特征大小完美匹配的角度分辨率。如此详细、大规模的观测是前所未有的。”

That "candy cane" in the center of the image is made of ionized gas and measures 190 light-years from end to end, NASA explains in a news release. It includes a prominent radio filament known as the Radio Arc, which forms the straight part of the candy cane, as well as filaments known as the Sickle and the Arches, which form the cane's handle.

NASA在新闻发布会上解释说，图片中心的“拐杖糖”是由电离气体构成的，从一端到另一端长达190光年。它包括一个著名的被称为无线电弧的无线电灯丝，它形成了“拐杖糖”的直线部分，以及被称为镰刀和拱门的灯丝，它形成了“拐杖糖”的手柄。

This labeled version of the GISMO image highlights the Arches, Sickle and Radio Arc that form a 'cosmic candy cane,' as well as other key features like Sagittarius A, home to a supermassive black hole at the center of our galaxy. (Image: NASA’s Goddard Space Flight Center)

GISMO gathered enough data to detect the Radio Arc after gazing into the sky for eight hours, making this the shortest wavelength where these strange structures have been observed by humans. These radio filaments mark the edges of a large bubble, researchers say, which was produced by some kind of energetic event at the galactic center.

在凝视天空8个小时后，GISMO收集了足够的数据来探测射电弧，使其成为人类观测到的这些奇怪结构的最短波长。研究人员说，这些无线电丝标记着一个大气泡的边缘，这个大气泡是由银河系中心的某种高能事件产生的。

The new microwave observations from GISMO are portrayed in green, for example, while blue and cyan reveal cold dust in molecular clouds where "star formation is still in its infancy," NASA explains. In yellow regions like the Arches or the Sagittarius B1 molecular cloud, we're looking at ionized gas in well-developed "star factories," courtesy of light from electrons that are slowed but not captured by the gas ions. Red and orange represent "synchrotron emission" in features like the Radio Arc and Sagittarius A, a bright region inhabited by a supermassive black hole.

例如，来自GISMO的新微波观测结果被描绘成绿色，而蓝色和青色显示了分子云中的冷尘埃，NASA解释说，“恒星形成仍处于初期阶段”。在像拱门或人马座B1分子云这样的黄色区域，我们看到的是在成熟的“恒星工厂”里的电离气体，这是由于电子减慢了速度，但没有被气体离子捕获。在射电弧和人马座A(一个由超大质量黑洞居住的明亮区域)等特征中，红色和橙色代表“同步加速发射”。

This image shows another view of the galactic center, thanks to infrared cameras on the Spitzer Space Telescope. (Image: Susan Stolovy (SSC/Caltech) et al./NASA, JPL-Caltech)

The center of our galaxy is largely obscured by clouds of dust and gas, preventing us from directly observing scenes like this with optical telescopes. We can still peek in other formats, though, such as infrared light — used by NASA's Spitzer Space Telescope, for instance, and the upcoming James Webb Space Telescope — or radio waves, including the microwaves detected by GISMO.

我们星系的中心很大程度上被尘埃和气体云所遮蔽，使我们无法用光学望远镜直接观测到这样的景象。尽管如此，我们仍然可以通过其他方式进行观测，比如美国宇航局的斯皮策太空望远镜使用的红外线，以及即将推出的詹姆斯韦伯太空望远镜，或者无线电波，包括GISMO探测到的微波。

In future missions, GISMO may help us see even deeper in space. Staguhn hopes to take GISMO to the Greenland Telescope, where it could produce vast sky surveys in search of the first galaxies where stars formed.

在未来的任务中，GISMO可能会帮助我们看得更远。斯塔格恩希望将GISMO带到格陵兰岛望远镜，在那里它可以进行大规模的天空观测，寻找第一个恒星形成的星系。

"There's a good chance that a significant part of star formation that occurred during the universe's infancy is obscured and can't be detected by tools we've been using," Staguhn says, "and GISMO will be able to help detect what was previously unobservable."

斯塔格恩说:“很有可能，发生在宇宙初期的恒星形成的重要部分被我们一直使用的工具所掩盖，无法被探测到。而GISMO将能够帮助探测到以前无法观测到的东西。”